RAUC: turn this into a configurable target

I am not using the generic rootfs target because it is optimized for
using fakeroot, and because it extracts that tarball from rootfs-common.
Rather than fighting the hooks (ROOTFS_XXX_POST_GEN_HOOKS is the only
thing which runs outside of fakeroot) and doing extra work by unpacking,
let's go all the way down to raw Makefile.

Change-Id: I075204291fbeac8d1af97a0a7c1254054ef1f594
diff --git a/package/czechlight-rauc/Config.in b/package/czechlight-rauc/Config.in
new file mode 100644
index 0000000..a04f412
--- /dev/null
+++ b/package/czechlight-rauc/Config.in
@@ -0,0 +1,13 @@
+config CZECHLIGHT_RAUC_ROOTFS
+	bool "Create RAUC update bundle"
+	select BR2_PACKAGE_CZECHLIGHT_CFG_FS
+	select BR2_PACKAGE_HOST_RAUC
+
+if CZECHLIGHT_RAUC_ROOTFS
+
+config CZECHLIGHT_RAUC_COMPATIBLE
+	string "HW compatibility string"
+	help
+	  Unique identifier which specifies what boards accept a given SW image.
+
+endif # CZECHLIGHT_RAUC_ROOTFS